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From: Lawrence D'Oliveiro <ldo@nz.invalid>
Newsgroups: comp.lang.python
Subject: Re: Relatively prime integers in NumPy
Date: Thu, 11 Jul 2024 21:43:47 -0000 (UTC)
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On Thu, 11 Jul 2024 11:35:44 -0700, Paul Rubin wrote:

> Two numbers a and b are coprime if math.gcd(a,b) == 1, I am pretty sure.
> That is true by definition(?) when a and b are both > 0.  Experiment
> indicates it seems to work even when one or both of a and b are
> negative, but I don't have a proof and haven't examined the
> implementation.  I don't know how gcd is mathematically defined in that
> situation.

You can derive the answer quite trivially by observing that negative 
numbers are smaller (less than, not greater than) positive numbers.